Needle driving device for sewing machines

ABSTRACT

This invention relates to an improved sewing machine needle operating mechanism in which a pivoting lever is included that is mounted on the frame of the machine for pivoted movement about a fulcrum located below the needle driving lever. The pivoting lever is mounted in an attitude that is practically parallel with the path of travel of the needle and the needle carrier.

United States Patent [1 1 Marforio [451 July 17, 1973 NEEDLE DRIVING DEVICE FOR SEWING MACHINES [75] Inventor: Nerino Martel-i0, Milan, Italy [73] Assignee: S.p.A. Virginie Rimoldl & C., Milan,

Italy [22] Filed: Dec. 30, 1971 [21] Appl. No.: 214,085

[52] 11.8. Cl. 112/221, 74/103 [51] Int. Cl D05b 55/14 [58] Field of Search 112/221, 220, 218 R; 74/589, 103

[56] References Cited UNITED STATES PATENTS 2,799,236 7/1957 Marforio et al 112/221 FOREIGN PATENTS OR APPLICATIONS 65,513 2/1969 Germany 4. 112/221 Primary Examiner-H. Hampton Hunter Attorney-John R. Bronaugh et al.

ABSTRACT 3 Claims, 3 Drawing Figures NEEDLE DRIVING DEVICE FOR SEWING MACHINES BACKGROUND OF THE INVENTION This invention refers to a needle driving device for a sewing machine and includes a needle supported by a needle clamp mounted for sliding movement on a needle bar fixed on the frame of the machine, the needle clamp sliding alternatively along the said needle bar by a driving lever moved by the main shaft by means of mechanisms fitted with a crank, the driving lever being pivoted on the said crank and with one end pivoted on the needle clamp and the other end guided by a suitable pivoting lever. In the sewing machines a device of the type mentioned is already known and it distinguishes itself by the fact that the needle clamp is made sliding easily and without jam-up along the needle bar which is fixed pratically and rectilinear. In practice, the needle clamp undergoes movements of few microns from the needle bar and they increase in correspondence with the extreme ends of the path so that the working stretch of the path which is used for the sewing stitch formation is that included between the two extreme ends and which is pratically rectilinear. The formation of the sewing stitches requires the descending of the needle under the needle plate to meet the looper always at the same level and moreover requires the lifting of the needle at a distance enough for it to keep the necessary distance from the work which runs on the machine in order not to interfere with possible ruffles, crossed seams, pleats or any other protrusion which could hinder the free running of the work. Thus, in the case of very thick fabrics, the run of the needle must be adeguately increased in order to eliminate any possible interference with the work placed under it.

Up to now the already known device had not allowed to increase the run of the needle clamp sufficiently so that it was not possible to sew very thick fabrics.

The aim of the present Patent Application is that of making it possible to sew very thick fabrics without changing the basic size of the needle driving device. In order to reach this aim, the technical problem to be solved was that to project a device of the type mentioned designed in a way that the working path which can be covered by the needle clamp is lengthened upwards.

To solve this technical problem it was designed a device according to this invention in which the pivoting lever is hinged on the driving lever in a position practically parallel to the path covered by the needle clamp and actually used by the needle bar andhas its fulcrum on the frame under the driving lever: I

The advantage obtained with the new needle driving device makes it possible to increase the run of the needle clamp without undergoing any trouble by about 25 percent in comparison with the run which could be obtained with the already known device.

Other characteristics and further advantages of the present invention will be clear from the specification which follows hereunder and from the enclosed drawings, of a preferred embodiment of realisation, wherein:

FIG. 1 shows a frontal view of the invention and mounted on a sewing machine;

FIG. 2 shows a perspective view of the invention; and

FIG. 3 shows the work scheme in elevation of the present invention.

With reference to the FIG. 1, a sewing machine is usually formed with a bed 1 which is the seating for the usual stitch forming devices, such as the loopers, not shown, which work together with a. needle 2 for the formation of the stitches, for example, of the overstitching chain stitch type. A feed dog 3 formed with serrations 4 moves the work forward as it is sewn by the stitching devices and by the needle.

Within the bed I a shaft 5 is placed lengthwise. It is shown in FIG. 2 the main shaft of the machine and is shown connected to those driven devices necessary for a complete and safe working of the machine.

The bed 1 is fitted with a work supporting plate 6 on which the work to be stitched is made to run by the feed dog 3, and on the side of this work supporting plate a vertical standard 7 is mounted. It defines a sup port for an oscillating shaft 8 (FIG. 2) which is connected with the main shaft 5 below by means of an arm 9 and a connecting rod 10. The oscillating shaft 8, the arm 9 which is supported in an adjustable way on the said shaft and the connecting rod 10 comprise the actuating mechanism of the needle driving device. In particular, the connecting rod 10 is mounted on a suitable counterbalanced crank 11 formed in the main shaft 5. Shaft 5 rotates continually so that, at each rotation the oscillating shaft 8 makes a complete oscillation. These oscillations are transmitted to the needle driving device by a crank 12 which is disc-like and protrudes out of the standard 7. The crank 12 has a crank pin 13 connecting it with the driving device formed by a driving lever 14 which pivots about the said crank pin 13 and which has one end in the form of a fork 15. A needle clamp 17 is operably connected to driving lever 17 by means of a pin 16.

The other end of the driving lever 14 is pivotably connected to a pin 18 projecting from the upper end of a pivoting lever 19. The opposite end of lever 19 has a suitable pin 20 (FIG. 1) that is set pratically at the same height as the work supporting plate 6 of the machine and is joumaled within standard 7.. A needle bar 21 is fixed to a bracket 22 of the standard 7. The pivoting lever 19 attached to the driving lever 14 as previously noted is disposed in such a position that it is parallel to the needle bar 21, which carries out the path of the movement of the needle clamp 17 in the way explained later on. The needle bar 2] acts as a guide for the needle clamp, and makes it possible to prevent the needle from capsizing or fluttering around the pin 16. Actually the fixed bar 21 does not cause the needle clamp 17 to move along a rectilinear path as both the said clamp and the pin 16, which fixes it to the driving lever-l4 already inove in a path which is pratically rectilinear. Actually this path takes on a lengthened S form which varies from rectilinear only by a few microns, about 6, so that the sliding of the needle clamp 17 along the needle bar 21 occurs easily and without jam-ups. The working length of the path is limited by extreme movements within whose limits the path is pratically rectilinear. The needle clamp 17 is reciprocably moved along this path by the crank 12 whose effective lever arm is about one sixth of the total length of the driving lever 14.

The crank 12 transmits its own oscillations of an amplitude of about 60 to the lever 14 by means of its crank-pin 13 set at a distance from the pin 16 amonting to two thirds of the total length of the lever 14. As the driving lever 14 is pivoted on the pivoting lever 19, the latter allows the movements-of the crank-pin 13 along the are x to be followed. The oscillations of the crank 12 are transmitted to the driving lever 14 which is compelled to move upwards and downwards rotating around the pin 18 which, in its turn, must move along an arc y, being fixed to the pivoting lever 19 fulcrumed at 20. When the crank 12 moves from the position shown by a continous line to the position shown by a dotted line, the lever 14 moves in the same direction and thus the pin 18 is compelled to move to the left because the lever 14 cannot be lengthened any more. Pin 18 must also descend because of the oscillation of the pivoting lever 19 around its pin 20. According to the position of pivoting lever 19, when the crank 12 gets to the position shown with a dotted line, the lever 14 has moved upwards so much that it drags to the right the pin 18 running along the arc y. In this way the needle clamp 17 can carry out movements along the needle bar 21 without any jam-up. The pivoting lever 19 is designed to pivot on the standard 7 in a position lower than the position of the driving lever 14 and in an attitude pratically parallel to the needle bar 21.

The lower positioning of the pivoting lever 19 allows the amplitude of the oscillations of the crank 12 to be increased only upwards so as to lengthen the path of the needle clamp upwards too and to allow thus very thick fabrics to be sewn. As can be seen from the enclosed figures, the needle bar 21 as well as the pivoting lever 19 are sloping in relation to the work supporting plate 6 toward the back side 7A of the machine, that is to say that they are not sloping in the direction of the movement of the work. This is due to the need of balancing the possible pressure that the work carries out on the needle when it is inside the fabric while the feed dog 3 starts its action on the said fabric.

1 claim:

1. In a sewing machine including a bed with a vertical standard, a work supporting surface, a needle carried in a needle clamp mounted for sliding movement on a needle bar fixed to the vertical standard, a main drive shaft and means including a pivotable crank and a pivotable driving lever operably connecting the drive shaft with the needle clamp, the improvement comprising a pivoting lever mounted on the standard in a position practically parallel to the path of travel of the needle clamp and having one end pivotally connected to the driving lever and the other end mounted on the vertical standard for pivotal movement about a fulcrum located below the driving lever.

2. An improved sewing machine drive as defined in claim 1 wherein said pivoting lever has its fulcrum located on the vertical standard at practically the same height as the work supporting surface of the machine bed.

3. An improved sewing machine drive as defined in claim 1 wherein the pivoting lever is practically parallel to the needle bar and both slope in relation to the work supporting surface of the machine toward the back side thereof in the direction of movement of the work.

2%? UNITED STATES PATENT oEFIc i r t CERTIFICATE OF CORRECTION Patent No. 3, 745, 951 Dated July 17, 1973 Inventofls) Nerino Marforio and that said Letters Patent are hereby corrected as shown below:

It is certified that error appears in the above-identified p atent Column 1, Line 7; after "214,085" insert i t 1 ----Claims priority, application Italy,-Februaryl 5, 1971, 20557 A/7l t Column 2; line 33, delete "17" second ocourrence and 1 substitute 14 Signed and sealed this 25th day of December 1973. i

i (SEAL) Attest: EDWARD MQELET HEmJE. RENE D. TEGTMEYER Attesting Officer Acting Commissioner of Patents 

1. In a sewing machine including a bed with a vertical standard, a work supporting surface, a needle carried in a needle clamp mounted for sliding movement on a needle bar fixed to the vertical standard, a main drive shaft and means including a pivotable crank and a pivotable driving lever operably connecting the drive shaft with the needle clamp, the improvement comprising a pivoting lever mounted on the standard in a position practically parallel to the path of travel of the needle clamp and having one end pivotally connected to the driving lever and the other end mounted on the vertical standard for pivotal movement about a fulcrum located below the driving lever.
 2. An improved sewing machine drive as defined in claim 1 wherein said pivoting lever has its fulcrum located on the vertical standard at practically the same height as the work supporting surface of the machine bed.
 3. An improved sewing machine drive as defined in claim 1 wherein the pivoting lever is practically parallel to the needle bar and both slope in relation to the work supporting surface of the machine toward the back side thereof in the direction of movement of the work. 